To de-clutter the flight deck and reduce cost and weight, some flight decks now use non-moving side-sticks and throttles that do not directly provide the pilot with awareness of control surface deflections. This paper compares how well aircraft state can be estimated with and without indications of control surface (elevator, aileron, rudder, and throttle) deflections by running a hybrid Extended Kalman Filter representing an optimal integration of continuous-time pilot vestibular input, discrete-time pilot visual scans of flight instruments, and immediate estimated aircraft state. This Model-Based Observer (MBO) is configurable to have or not have awareness of control surface deflections. Computational experiments examine a variety of maneuvers, particularly in conditions conducive to vestibular illusions without good indicators to (or visual scanning by) the pilot of aircraft state. These experiments all show a clear trend of increasing estimation error when the MBO has no awareness of control surface deflections during a period of pilot distraction from visual scans. When good scanning behavior is performed, there is little difference in estimation error, implying that the effects of diminished control state awareness are negated.